Electrolytic smoothing of conductive parts is a commonly employed technique. Two well-known processes are called electrochemical deburring (ECD) and electro polishing. Such smoothing operations are herein referred to as deburring.
Conventional ECD uses a highly conductive salt solution as the electrolyte. Because the solution is so conductive, the anodic part being deburred must be spaced extremely closely (separation of 10 to 30 mils) for effective, controlled metal removal. Electropolishing employs hazardous hot acidic electrolytes and is only effective in removing small burrs.
An improvement to these typical processes is described in U.S. Pat. Nos. 4,405,422, and 4,411,751, by the same inventor and incorporated herein by reference. These patents describe a process employing a less-conductive and less harzardous electrolyte that accomplishes deburring with a much larger separation between electrodes and part or parts, typically 1 to 3 inches.
In either process, however, it can be difficult and expensive to deburr complex-shaped parts and especially parts with burrs which do not protrude from the part being deburred; such buried burrs are reached by little if any current, and thus are not fully removed in the deburring process. It has been the practice in such instances to construct cathodically connected probes of a size and shape to introduce cathodic potential near the locations of such shielded burrs. Although this technique if carefully done will effectively remove the burr, it creates a number of problems. For example, a large or difficult to see burr may come into contact with the cathodic probe during operation and create a short circuit which can destroy the probe, boil the electrolyte, and fuse the burr material, any of which would prevent successful completion of the deburring process. In addition, it can be difficult, expensive, and time consuming to construct and cathodically connect these probes. Also, the probes in effect create a complex-shaped cathode which surrounds and/or penetrates the part. Accordingly, it is not possible to move the part relative to the cathode during deburring. As a result, this process does not readily lend itself to automation or deburring of many parts at the same time.